I have always understood that one should never iron over the printed area on T-shirts - usually they carry a warning to that effect.

How anyone can wear any garment that has not been ironed beats me!! The only items I do not iron are my kilt hose/socks and footwear! All my bed-linen, towels, tea-towels, handkerchiefs, etc. are carefully ironed before being put away following laundry. That's the way I was brought up!!!